Recently, in the dairy industry and in other industries dealing in consumer goods such as food products, there has been a growing trend to the use of thin-walled poly-bags for packaging purposes. Milk may be found in pouches and the pouches may be found in overbags. Potato chips, cereals, fertilizers, kitty litter, pet food and laundry detergents, are examples of other products found in poly-bags which are usually hermetically sealed as by heat sealing to preserve freshness. Vegetables and bakery products are often packaged in poly-bags which may be closed by pressure-sensitive adhesive tapes or reusable fastening devices. All of these products share the common steps of loading a predetermined weight, number or volume of a commodity into a bag and subsequently closing the bag hermetically or otherwise. The speed with which the filling and closing operations can be accomplished is governed by a number of factors, not the least of which is the capacity of the filling and closing apparatus itself. Other constraints are found in the feeding, weighing (or counting) and removal stages.
Many filling machines in the past have utilized gravity feed for the commodity to be packaged, the commodity passing downwardly through a hopper into a bag positioned therebeneath. Once the bag was properly filled it was removed from the filling location and passed, as by a conveyor to a closure station. In many instances, the hopper could double as a counting or weighing device to determine the exact amount of the commodity to be allowed to fall into the bag.
If the bag was to be hermetically sealed, or even if the opening was to be brought together to form a "pony tail, " the machine designer was faced with the random location of the bag sides after the bag had fallen from the hopper. If the bag was to be sealed it was necessary to bring the bag sides together face to face for a bar sealer. If the bag sides were to be gathered for a "pony tail" configuration it was necessary to somehow encircle the bag sides and bring them together into the "pony tail" for application of the appropriate fastener or closure member. Needless to say the equipment for this step preliminary to actual closure was, of necessity, sophisticated and expensive.